In a statement Tuesday, Feinstein expressed dismay at "how easily these machines could be hacked into and election results distorted," based on her reading of the report.

"The findings are yet another reason that states and counties should consider a move to optical scan machines that provide an auditable, individual without having to rely on a separate printer," she went on.

The study, commissioned by California Secretary of State Debra Bowen, focused on machines made by Diebold Election Systems, Hart InterCivic, and Sequoia Voting Systems. The University of California researchers who conducted the testing rattled off a list of security weaknesses they were able to exploit in each of the machines--although they didn't attempt to quantify how difficult it was to carry out the hacks.